Skip to main content
NCBI home page
Neural Regeneration Research logoLink to Neural Regeneration Research
. 2023 May 12;18(12):2767–2772. doi: 10.4103/1673-5374.373715

Ketogenic diet alleviates cognitive dysfunction and neuroinflammation in APP/PS1 mice via the Nrf2/HO-1 and NF-κB signaling pathways

Jingwen Jiang 1, Hong Pan 1, Fanxia Shen 1, Yuyan Tan 1,*, Shengdi Chen 1,2,*
PMCID: PMC10358659  PMID: 37449643

graphic file with name NRR-18-2767-g001.jpg

Key Words: Alzheimer’s disease, APP/PS1 mice, cognitive impairment, ketogenic diet, neuroinflammation, nuclear factor-kappa B pathway, nuclear factor-erythroid 2-p45 derived factor 2/heme oxygenase-1, therapeutic benefits

Abstract

Alzheimer’s disease is a progressive neurological disorder characterized by cognitive decline and chronic inflammation within the brain. The ketogenic diet, a widely recognized therapeutic intervention for refractory epilepsy, has recently been proposed as a potential treatment for a variety of neurological diseases, including Alzheimer’s disease. However, the efficacy of ketogenic diet in treating Alzheimer’s disease and the underlying mechanism remains unclear. The current investigation aimed to explore the effect of ketogenic diet on cognitive function and the underlying biological mechanisms in a mouse model of Alzheimer’s disease. Male amyloid precursor protein/presenilin 1 (APP/PS1) mice were randomly assigned to either a ketogenic diet or control diet group, and received their respective diets for a duration of 3 months. The findings show that ketogenic diet administration enhanced cognitive function, attenuated amyloid plaque formation and proinflammatory cytokine levels in APP/PS1 mice, and augmented the nuclear factor-erythroid 2-p45 derived factor 2/heme oxygenase-1 signaling pathway while suppressing the nuclear factor-kappa B pathway. Collectively, these data suggest that ketogenic diet may have a therapeutic potential in treating Alzheimer’s disease by ameliorating the neurotoxicity associated with Aβ-induced inflammation. This study highlights the urgent need for further research into the use of ketogenic diet as a potential therapy for Alzheimer’s disease.

Introduction

Alzheimer’s disease (AD) is a progressive neurodegenerative disease marked by cognitive decline and subsequent mental and behavioral impairments. It is the most frequent form of dementia, with an insidious beginning and sluggish progression (Lane et al., 2018). The pathogenesis of AD remains incompletely elucidated, yet existing literature indicates a multifactorial etiology involving genetic, environmental, and lifestyle factors. The amyloid hypothesis has gained significant traction in the scientific community. This hypothesis proposes that the aggregation of amyloid-beta (Aβ) peptides into plaques impairs synaptic communication and provokes neuroinflammation (Selkoe and Hardy, 2016). Despite ongoing efforts, the development of efficacious AD treatments necessitates more comprehensive understanding of the intricate mechanisms underlying the disease. There are currently few medications effective in lowering the risk of developing AD or in slowing disease progression, and the contentious approval of an IgG1 anti-Aβ antibody in 2021 aimed at the removal of Aβ plaques may be the only success to date (Asher and Priefer, 2022). As a result, public health is focusing heavily on preventative measures to promote healthy brain aging, with the objective of lowering the burden of cognitive impairment and dementia in the older population.

Researchers investigating the neuropathology and origins of AD have uncovered a diverse set of intricate molecular fingerprints. It is generally accepted that the Aβ aggregation and tau hypotheses have slowly come to dominate in AD-related research (Sharifi-Rad et al., 2020; Ashrafian et al., 2021; Ciccone et al., 2021). Moreover, hypometabolism (Szablewski, 2021), mitochondrial dysfunction (Atlante et al., 2022; Zeng et al., 2022), inflammation (Bajwa and Klegeris, 2022), and oxidative stress (Beura et al., 2022) have all been linked to the etiopathogenesis of AD. New evidence suggests that nutritional and metabolic treatments may be able to address these problems, which have been challenging to tackle owing to a lack of effective prevention and therapeutic strategies (Shohayeb et al., 2018). The ketogenic diet (KD) is a nutritious dietary pattern that is low in carbs, high in fat, and moderate in protein. In a limited sample of patients, Krikorian et al. (2012) reported that 6 weeks on a KD enhanced verbal memory performance versus patients on a high carbohydrate diet. Medium chain triglyceride-containing KDs have been shown to enhance cognitive performance in Aβ-positive individuals, restoring mitochondrial function and decreasing Aβ toxicity (Hertz et al., 2015; Wu et al., 2020). These findings are encouraging, particularly if the benefits are sustained in longer-term research. The mechanism of neuroprotection afforded by a KD is still unknown. However, several studies have shown that a KD is associated with a reduced inflammatory response and oxidative damage (Hersant and Grossberg, 2022; Kong et al., 2022; Rojas-Morales et al., 2022).

Neuroinflammatory reactions are related to the development of AD in experimental trials. As immune cells of the central nervous system, activation and proliferation of microglia and astrocytes play a critical role in the control and release of inflammatory mediators and are thought to be essential pathological indicators of neuroinflammation (Guo et al., 2022). Reduced expression of the transcription factor, nuclear factor-erythroid 2-p45 derived factor 2 (Nrf2), and its target genes (NQO1, HO-1, and GCLC), as well as modification of Nrf2-related pathways, are reported in the brains of patients with AD (Ballard et al., 2011). The Nrf2 transcription factor is an important regulator of inflammation and can decrease the inflammatory responses generated by inflammatory factors such as nuclear factor-κB (NF-κB) (Saha et al., 2020). There have been few studies to determine if a KD can improve cognitive function and the underlying mechanisms. Thus, we sought to determine if a KD controls Nrf2 in the amyloid precursor protein (APP)/presenilin 1 (PS1) mouse model of AD, and whether it exerts anti-inflammatory effects by reducing activity of the NF-κB signaling pathway.

Methods

Animals and diet

APP/PS1 (B6.Cg-Tg[APPswe,PSEN1dE9]; MMRRC Cat# 034832-JAX, RRID: MMRRC_034832-JAX) double-mutant transgenic mice derived from the C57BL/6J strain were kindly provided by University of Tübingen, Tübingen, Germany. Specific pathogen-free C57BL/6J mice were purchased from the Zhejiang Branch of Vital River Laboratory Animal Technology Co. Ltd., China (license No. SCXK (Zhe) 2019-0001). Control mice were age-matched wild-type (WT) littermates without the transgene. In all tests, male mice were used. Mice were kept in groups of five in cages at room temperature (22 ± 1°C) on 12/12-hour light/dark cycles. All animal experiments were conducted with the approval of the Ethics Committee at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine (approval No. 2018-243) and in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals (8th ed, National Research Council, 2011). All procedures were carried out in compliance with the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines (Percie du Sert et al., 2020).

Dyets, Inc. (Bethlehem, PA, USA) provided the KD (HF93.5) and control diet (CD) (HF85-C). In terms of calories, the KD had 93.5% fat, 4.7% protein, and 1.8% carbohydrate. A typical laboratory diet of 11.5% fat, 10.4% protein, and 78.1% carbohydrate (in kcal) served as the CD. Multiple vitamins and minerals were present in both the KD and CD. The specific ingredients are shown in Table 1.

Table 1.

Ingredients in ketogenic and control diets

Ingredient g/kg
Control diet
Caisein 100
DL-methionine 1.5
Sucrose 0
Comstarch 0
Dyetrose 751.5
Shortening 0
Corn oil 50
Cellulose 50
Mineral Mix #200000 35
Vitamin Mix #300050X 10
Choline bitartrate 2
Ketogenic diet
Caisein 45
DL-methionine 1.5
Dyetrose 17
Cellulose 50
Lard 260
Anhydrous Milkfat 100
Corn oil 50
Mineral Mix #200000 35
Vitamin Mix #300050X 1
Choline bitartrate 2
Open in a new tab

Experimental design

The use of 3-month-old male mice was based on the intended aim of observing treatment effects at the early stages of AD progression and amyloid plaque formation (Bilkei-Gorzo, 2014, Webster et al., 2014). A previous study found that male and female rodents respond differently to high-fat diet challenge, with female mice showing a higher preference for high-fat diet, dramatic increase in visceral fat, impaired glucose tolerance, and decreased energy expenditure compared to male mice (Maric et al., 2022). Thus, we selected male mice for our experiment to reduce variability and increase the robustness of our statistical analyses. Three-month-old male APP/PS1 mice were randomly assigned to one of two groups (n = 12 per group): (1) AD model (APP/PS1) and KD treatment group (APP/PS1+KD); and (2) AD model (APP/PS1) and CD treatment group (APP/PS1+CD). The control group (WT+CD, n = 12) consisted of 3-month-old male WT mice treated with CD. All groups had ad libitum supply of water. Animals were given the CD ad libitum. The KD was provided in an amount equivalent to the daily calories consumed by WT mice. The timeline of the experiment is shown in Figure 1.

Figure 1.

Figure 1

Open in a new tab

Experimental timeline.

Behavioral testing

Novel object recognition test

A typical behavioral test used to examine hippocampus-dependent recognition memory is the novel object recognition test (NORT). It is based on the fact that animals spend more time analyzing a novel object than a known one (Leger et al., 2013). To test the cognitive ability of the mice, the test is conducted in an open empty box (40 × 40 × 40 cm3) with two items that are approximately the same height and volume, yet differ in shape and appearance. During the familiarization phase (Figure 2A), mice were exposed to two identical objects situated at an equal distance in either corner for 10 minutes, then the box was cleaned using 75% ethanol. After 1 hour, the animal was returned to the box and tested again. During the second phase (Figure 2A), one of the initial objects was replaced with a new item of comparable mass, and the animal was allowed to explore freely for approximately 5 minutes. NORT data were evaluated using a video tracking system (Softmaze; Xinruan, Shanghai, China). The recognition index (%) for new object exploration was determined as follows: time spent on novel object/(time spent on novel object + time spent on familiar item) × 100.

Figure 2.

Figure 2

Open in a new tab

Ketogenic diet treatment ameliorates impaired working memory and reduces amyloid deposition in the hippocampus and cortex of 6-month-old APP/PS1 mice.

(A) Timeline for the novel object recognition test. (B) Recognition index for the groups presented in A. (C) Schematic diagram of the Y-maze spontaneous alternation test. (D) Histograms show no significant difference between the three groups in terms of total arm entries in the Y-maze spontaneous alternation test. (E) Histograms show a lower proportion of alternations in the APP/PS1+CD group and significant recovery in the APP/PS1+KD group in the Y-maze spontaneous alternation test (n = 12 per group). (F) Images of representative immunohistochemical staining of Aβ1–42 plaques in the hippocampus of mice in all three groups. Scale bars: 200 μm. (G) Histograms show the percentage of Aβ1–42 area in the hippocampus and cortex (n = 6 per group). Data are shown as mean ± SEM. *P < 0.05, ***P < 0.001, ****P < 0.0001 (one-way analysis of variance followed by Tukey’s post hoc test). Aβ: Amyloid-β; CD: control diet; KD: ketogenic diet; n.d.: not detected; WT: wild-type.

Y-maze spontaneous alternation test

Spontaneous alternation in the Y-maze (which is used to measure spatial working memory) is based on the natural curiosity of mice (Kraeuter et al., 2019). Testing takes place in a Y-shaped maze with three equal-sized arms constructed of opaque plastic. The arms (35 × 5 × 10 cm3) were placed at a 120° angle from each other and labeled A, B, and C (Figure 2C). The mice were placed at the terminal of arm B and permitted to freely explore the three arms for 8 minutes. The proportion of alternation was calculated by recording the number of arm entries and triads. Total arm entries were recorded manually by the observer (who was blinded to the treatment) or automatically by Supermaze (Xinruan). A successive entry in three separate arms was classified as an alternation. An entrance was recorded when all four limbs were within the arm. The proportion of alternations (entry into a different arm from the previous two) was computed using the following formula: alternations / (arm entries – 2) × 100%.

Tissue collection

At 6 months of age, the animals underwent behavioral testing and were then placed in a chamber filled with anesthetic vapor (approximately 0.6 mL liquid isoflurane per liter of chamber volume) (Shanghai Yuyan Scientific Instrument Company, Shanghai, China, Cat# 100150) until respiration ceased. This typically occurred within 2 minutes (Overmyer et al., 2015). The cortex and hippocampus of mice (n = 6) were dissected into cold phosphate-buffered saline (PBS) (Servicebio, Wuhan, China, Cat# G0002) and immediately stored at –80°C for subsequent study. The remaining animals (n = 6) were perfused with saline, postfixed in 4% paraformaldehyde (Servicebio, Cat# G1101) at 4°C overnight, then dehydrated for 72 hours in 30% sucrose solution. Next, the brains were frozen and embedded in optimal cutting temperature (OCT) compound (Sakura, Torrance, CA, USA, Cat# 4583) before being sliced into uniform pieces (12 µm) with a microtome (Leica, Wetzlar, Germany). Frozen sections were thawed and placed on positively charged slides (ProbeOn Plus; Thermo Fisher Scientific, Waltham, MA, USA) before storage at –20°C.

Immunofluorescent staining

Antigen retrieval from frozen brain slices required 20–30 minutes of microwaving (Midea, Foshan, Guangdong, China, Cat# M1-211A) in citrate buffer (pH 6.0) (Servicebio, Cat# G1202). A blocking mixture of 10% bovine serum albumin (BSA) (Aladdin, Shanghai, China, Cat# B265994) and 0.3% Triton X-100 (Aladdin, Cat# T434386) in PBS was applied after 30 minutes. Sections were incubated overnight at 4°C with primary antibodies diluted in normal goat serum solution (2%) (Beyotime, Shanghai, China, Cat# C0265). Rabbit anti-Aβ1–42 antibody (1:500, Cell Signaling Technology, Danvers, MA, USA, Cat# 14974, RRID: AB_2798671), anti-glial fibrillary acidic protein (GFAP) antibody (1:200, Cell Signaling Technology, Cat# 12389, RRID: AB_2631098), and anti-AIF-1/ionized calcium-binding adapter molecule 1 (Iba1) antibody (1:50, Cell Signaling Technology, Cat# 17198, RRID: AB_2820254) were used as primary antibodies at 4°C overnight. GFAP is a marker for activated astrocytes, while Iba1 is a marker for activated microglia. After the primary antibody incubation, the slices were rinsed extensively with PBS and then treated with Alexa 488- or Alexa 594-conjugated goat anti-rabbit IgG secondary antibodies (1:500; Jackson ImmunoResearch Laboratories, West Grove, PA, USA, Cat# 111-585-003, RRID: AB_2338046 [Alexa 488-] and AB_2338059 [Alexa 594-]) for 1 hour at 37°C in the dark. Staining of nuclei for 10 minutes in 4′,6-diamidino-2-phenylindole (DAPI) (Beyotime, Cat# C1005) was followed by washing in PBS. The Zeiss AxioVert A1 fluorescence microscope (Oberkochen, Germany) and a digital slide scanner (Pannoramic DESK; 3DHISTEK, Budapest, Hungary) were used to capture images. Immunofluorescence analysis was performed on brain sections from the cortex and hippocampus fields, with three regions of interest randomly selected per section at 20× zoom level in scanning. The same imaging parameters were used for all samples. Quantification of immunofluorescence-positive area and cells were performed on equal-area immunostaining images using ImageJ software (1.53c, NIH, Bethesda, MD, USA; Schneider et al., 2012). The results were averaged, with six samples per group, and all quantitative analyses were conducted by an investigator blinded to the experimental groups.

Western blotting

Tissue lysate buffer (Absin, Shanghai, China, abs9225) with 1 mM phenylmethanesulfonyl fluoride (Sigma-Aldrich, St. Louis, MO, USA, Cat# P7626) and EASYpack Protease Inhibitor Cocktail (Roche, Basel, Switzerland, Cat# 5892970001) were mixed with brain tissue for 30 minutes at 4°C. The supernatant of lysates was recovered after centrifuging for 20 minutes at 12,000 × g and at 4°C. The manufacturer’s instructions were followed to successfully extract nuclear and cytoplasmic proteins using the Nuclear and Cytoplasmic Protein Extraction Kit (Beyotime, Cat# P0027). Protein concentrations were measured using the bicinchoninic acid (BCA) protein assay reagent (Beyotime, Cat# P0010). Samples were denatured by heating and then separated by gel electrophoresis with 4–15% SDS-PAGE gels (BeyoGel Plus PAGE; Beyotime, Cat# P0520S). Proteins were transferred onto polyvinylidene difluoride membranes. Nonspecific binding was reduced by incubating the membranes in blocking solution (Beyotime, P0023B) for 30 minutes. After blocking, the membranes were treated with rabbit primary antibodies against Nrf2 (1:1000, Cell Signaling Technology, Cat# 12721, RRID: AB_2715528), heme oxygenase-1 (HO-1) (1:1000, Cell Signaling Technology, Cat# 5853, RRID: AB_10835857), phospho-NF-κB inhibitor alpha (IκBα) (1:1000, Cell Signaling Technology, Cat# 2859, RRID: AB_561111), NF-κB p65 (1:1000, Cell Signaling Technology, Cat# 8242, RRID: AB_10859369), histone H3 (1:1000, Cell Signaling Technology, 4499, RRID: AB_10544537), and β-actin (1:1000, Servicebio, Cat# GB111364) at 4°C overnight. Horseradish peroxidase-conjugated secondary antibodies (Beyotime, Cat# A0208) were used at 37°C for 1 hour. Protein bands of interest were visualized by enhanced chemiluminescence (Beyotime, Cat# P0018S) with the Tanon gel imaging system (Tanon, Shanghai, China, Cat# 1600). The optical density ratio of plasma proteins to β-actin, as well as the optical density ratio of nuclear proteins to histone H3, were analyzed using ImageJ software (1.53c).

Cytokine measurement

Analysis of proinflammatory cytokines (interleukin [IL]-1β and IL-6) and an anti-inflammatory cytokine (IL-10) was performed using the Mouse Premixed Multi-Analyte kit (R&D Systems, Minneapolis, MN, USA, Cat# LXSAMSM-04) on lysates derived from brain tissue (cortex and hippocampus). Quantification of total protein content in each sample was performed using the BCA protein assay (Thermo Fisher Scientific, Cat# 23227). The results were related to BSA standards to enable comparisons. Concentrations of tumor necrosis factor α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1/CCL-2) were determined using commercially available enzyme-linked immunoassay kits (Absin, Cat# abs520010 and Cat# abs520016), in accordance with the manufacturer’s instructions.

Statistical analysis

No statistical methods were used to predetermine sample sizes. However, our sample sizes are similar to those reported in a previous publication (Xu et al., 2022). Biochemical and histological analyses were performed in a blinded manner with regard to genotype and treatment, while in vivo microscopy and analysis were performed blinded. The data are all presented with mean ± SEM. For analysis, both GraphPad Prism 9.0 (GraphPad Software, San Diego, CA, USA) and SPSS Statistics 20.0 (IBM Corp, Armonk, NY, USA) were used. The data were examined by one-way analysis of variance followed by Tukey’s post hoc test. The difference was determined to be statistically significant when P < 0.05.

Results

KD ameliorates cognitive deterioration in APP/PS1 mice

The cognitive capacity of APP/PS1 mice was evaluated using the NORT test and Y-maze spontaneous alternation test after mice had been fed a KD for a period of 3 months. KD treatment resulted in a substantial increase in the recognition index of APP/PS1 mice (P < 0.001, Figure 2B), demonstrating that the new item was preferred. In contrast, CD treatment resulted in a lower ratio, which suggests that the new item was not favored. To evaluate the spatial working memory of mice, the Y-maze spontaneous alternation test was used. Despite the KD intervention group exhibited a reduction in body weight compared to in the APP/PS1 mice with CD treatment (Additional Figure 1 (293.5KB, tif) ), there was no significant difference in the total number of arm entries between the three groups (P > 0.05, Figure 2D). This demonstrates that KD did not have an effect on locomotor activity of the APP/PS1 mice. The rate of spontaneous alternation in WT mice fed a CD was significantly greater than the rate in the APP/PS1+CD group (P < 0.0001) and APP/PS1+KD group (P < 0.05, Figure 2E). The rate of spontaneous alternation was considerably higher in the KD treatment group compared with the APP/PS1+CD group (P < 0.001). In general, our findings show that a KD could alleviate the working memory deficit seen in APP/PS1 mice.

KD causes a reduction in the accumulation of amyloid plaque deposition in APP/PS1 mice

The amyloid protein is widely acknowledged as a significant contributor to the pathogenesis of AD. Aβ plaques (which are often composed of the Aβ1–42 type) are an example of a common pathogenic trait connected to AD (Caballero et al., 2020). Immunofluorescence experiments showed a much greater intensity of Aβ1–42 immunofluorescence in the brains of APP/PS1 mice than WT animals (Figure 2F and G). Compared with APP/PS1 animals with CD treatment, the Aβ plaque-positive area in the hippocampus of APP/PS1 mice with KD showed a statistically significant reduction (P < 0.0001).

KD suppresses reactive gliosis in the brain of APP/PS1 mice

Multiple studies have shown that Aβ-induced neuroinflammation is associated with neurodegenerative processes characteristic of AD (Ardura-Fabregat et al., 2017; Anderson and Vetter, 2019), and that activation of astrocytes and microglia may contribute to disease pathogenesis. Microglial and astrocyte activity is well accepted as a measure of neuroinflammation (Wang et al., 2021). Here, immunohistochemical analysis revealed an increase in Iba1-positive microglia in APP/PS1 mice, indicating that microglia activation was higher than WT mice. Iba1-positive microglia were greatly decreased in both the cortex and the hippocampus as a result of KD, thereby reflecting less neuroinflammatory reactions. In addition, GFAP expression was upregulated in the neocortex and hippocampus of APP/PS1 model mice. However, this increase was dramatically decreased by KD therapy. According to these results, microglia and astrocyte activation are effectively suppressed by KD treatment in APP/PS1 animals (Figure 3A–D).

Figure 3.

Figure 3

Open in a new tab

Ketogenic diet decreases microgliosis in 6-month-old APP/PS1 mice.

(A) Representative immunofluorescence staining of GFAP (red), Iba-1 (green), and DAPI (blue) in the hippocampus of WT+CD, APP/PS1+CD, and APP/PS1+KD mice. (B) Representative immunofluorescence staining of GFAP (red), Iba-1 (green), and DAPI (blue) in the cortex of each group. Scale bars: 50 μm in A and B. (C,D) Quantification of the number of GFAP+ astrocyte and Iba-1+ microglia in the hippocampus (C) and cortex (D) of WT+CD, APP/PS1+CD, and APP/PS1+KD mice. n = 6 per group. Data are shown as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 (one-way analysis of variance followed by Tukey’s post hoc test). CD: Control diet; DAPI: 4′,6-diamidino-2-phenylindole; GFAP: glial fibrillary acidic protein; Iba1: ionized calcium-binding adapter molecule 1; KD: ketogenic diet; WT: wild-type.

KD reduces proinflammatory cytokine levels in APP/PS1 mice

The release of several cytokines contributes uniquely to the process of neuroinflammation. Because of this, we investigated the production of a variety of cytokines related to Aβ deposits, including IL-1β, IL-6, and TNF-α, as well as the anti-inflammatory cytokine, IL-10. Compared with the WT+CD group, production of IL-1β (P < 0.001), IL-6 (P < 0.01), and TNF-α (P < 0.05) were considerably increased in both the cortex and hippocampus of APP/PS1 mice treated with CD. However, the KD therapy group showed a significant reduction in IL-1β, IL-6, and TNF-α levels in both the cortex and hippocampus (P < 0.05 for each variable). The Luminex test showed a significant increase in IL-10 production in the cortex (P < 0.05). MCP-1/CCL2 is one of the primary chemokines that controls the recruitment and activation of monocytes and microglia (Zhang and Luo, 2019). KD therapy resulted in a substantial decrease in the levels of cortical MCP-1 (P < 0.05). This suggests that KD may be able to reduce neuroinflammation in the cerebral cortex and hippocampus of APP/PS1 animals (Figure 4A and B).

Figure 4.

Figure 4

Open in a new tab

Ketogenic diet reduces proinflammatory cytokine levels in 6-month-old APP/PS1 mice.

(A) Levels of IL-1β, IL-6, and IL-10 in the cortex and hippocampus of WT+CD, APP/PS1+CD, and APP/PS1+KD mice were determined using the Luminex assay. (B) Levels of TNF-α and MCP-1/CCL-2 in the cortex and hippocampus of WT+CD, APP/PS1+CD, and APP/PS1+KD mice were measured by enzyme linked immunosorbent assay. n = 6 per group. Data are shown as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 (one-way analysis of variance followed by Tukey’s post hoc test). CD: Control diet; IL: interleukin; KD: ketogenic diet; MCP-1: monocyte chemoattractant protein-1; TNF-α: tumor necrosis factor α; WT: wild-type.

KD regulates neuroinflammation via the Nrf2/HO-1 pathway

The transcription factor, Nrf2, plays a pivotal role in regulating innate immune responses. Translocating from the cytoplasm to the nucleus and binding to antioxidant response areas of DNA, Nrf2 activates transcription of cytoprotective genes in response to oxidative stress. Parkinson’s disease, AD, and amyotrophic lateral sclerosis are a few of the degenerative diseases linked to reduced Nrf2 activity in humans. According to recent research, activating Nrf2 has anti-inflammatory benefits via interactions with the NF-κB pathway (Sandberg et al., 2014). Here, we used western blotting to examine Nrf2 and inflammatory protein expression in the cortex and hippocampus of the brain. In the cortex and hippocampus of APP/PS1 mice, KD treatment considerably boosted expression of cytoplasmic Nrf2 and HO-1, while significantly decreasing expression of cytoplasmic phospho-IκBα (Figure 5A and B). The levels of nuclear NF-κB were reduced and nuclear Nrf2 increased owing to KD (Figure 5C and D). These results suggest that a KD may directly elicit a protective response in APP/PS1 model mice by means of the Nrf2/HO-1 pathway. Furthermore, the efficacy of these responses may be regulated by neuroinflammation through the NF-κB signaling pathway.

Figure 5.

Figure 5

Open in a new tab

Ketogenic diet regulates the Nrf2/HO-1 and NF-κB signaling pathways of 6-month-old APP/PS1 mice.

(A) Expression of cytoplasmic Nrf2, HO-1, and p-IκBα in the cortex and hippocampus was detected by western blotting. (B) Quantification of cytoplasmic Nrf2/β-actin, HO-1/β-actin, and p-IκBα/β-actin in the hippocampus and cortex. (C) Expression of nuclear Nrf2 and NF-κB in the cortex and hippocampus was detected by western blotting. (B) Quantification of nuclear Nrf2/histone H3 and NF-κB/histone H3 in the hippocampus and cortex. n = 6 per group. Data are shown as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001 (one-way analysis of variance followed by Tukey’s post hoc test). CD: Control diet; KD: ketogenic diet; HO-1: heme oxygenase-1; NF-κB: nuclear factor-κB; Nrf2: nuclear factor-erythroid 2-p45 derived factor 2; p-IκBα: phospho-IkB-alpha; WT: wild-type.

Discussion

KDs are rich in fat, high in medium chain triglycerides, and low in carbs. In the absence of glucose, KDs stimulate the synthesis of ketone bodies, which fuel the brain. Dietary therapy has been shown to aid cognitive development in epileptic children with pharmacoresistant epilepsy (IJff et al., 2016). Although the published evidence is scarce, the potential benefits of a KD in neurodegenerative diseases and cognitive decline have already been recognized (Tao et al., 2022). The primary goal of this study was to examine the effects of KD consumption in AD animal models.

In the present study, we discovered that KD administration for 3 months can protect APP/PS1 mice from learning and memory problems. In addition to improving cognitive functions, KD reduced Aβ deposition, decreased microgliosis, and alleviated neuroinflammation. Furthermore, a KD directly activated protective responses in APP/PS1 model mice via the Nrf2/HO-1 pathway. These findings suggest that a KD can ameliorate AD-like pathological changes and enhance learning and memory capacity, most likely by activating the Nrf2 pathway and influencing neuroinflammation via the NF-κB signaling pathway. Together, this reduced neuroinflammation and neurotoxic Aβ accumulation. KD is a very promising therapeutic option for AD management owing to its demonstrated efficacy and safety in treating refractive epilepsy (van Berkel et al., 2018).

Given the growing interest in the reduced systemic inflammation described with KD, it is a plausible strategy to influence cognitive decline and development in AD. There have been several modest human studies showing that following a KD program improves cognition in people with dementia (Vinciguerra et al., 2020). However, few mechanisms at the macro level have been described. Decreased energy availability for neurons has been linked to the early stages of AD, including disruption of glucose metabolism and hyperinsulinemia (Lilamand et al., 2020). It is now established that there is a connection between abnormal glucose metabolism and the neuroinflammation associated with AD. In the absence of glucose, the brain may make use of ketone bodies, which are the byproduct of fatty acid oxidation (Lilamand et al., 2021). There are several hypotheses as to why ketosis is so helpful for metabolic disorders. Common causes include the insulin-sensitizing effects of lower blood sugar levels (ketosis) (Hussain et al., 2012), weight loss (as a result of ketosis) (Gibson et al., 2015; Westman et al., 2006), improved mitochondrial function (Noh et al., 2004; Nylen et al., 2009), and reduced systemic inflammation (Ruskin et al., 2009; Shen et al., 2017). Dementia researchers are beginning to consider neuroinflammation as a key player in the development of disease (Morgan et al., 2019). Anti-inflammatory proteins including nucleotide-binding domain and leucine-rich repeat containing protein 3 (NLRP3) and C-terminal binding protein (Youm et al., 2015; Shen et al., 2017) are produced at higher rates during ketosis. These changes can lead to a reduction of systemic inflammation (Ruth et al., 2013).

Two important transcription factors, Nrf2 and NF-κB, were the focus of our research. We found that KD therapy significantly elevated cytoplasmic Nrf2 and HO-1 expression in the brain and hippocampus of APP/PS1 mice. Researchers have shown a decrease in Nrf2 activity in the brains of patients with AD, indicating a possible interaction (Bahn and Jo, 2019). Compared with their WT counterparts, AD transgenic mice lacking Nrf2 showed higher levels of GFAP, Iba-1, and CD11b, which resulted in enhanced astrogliosis and microgliosis (Rojo et al., 2018). A lack of Nrf2 accelerates the inflammatory process in the brain after traumatic brain injury by activating NF-κB (Pan et al., 2012). Under stress conditions, Nrf2 leaves its cytoplasmic association with Keap1, moves into the nucleus, and forms a binding complex with antioxidant response element. The crux of Nrf2-mediated NF-κB inhibition is the ability of Nrf2 to induce the transcription of genes encoding phase II detoxifying enzymes, such as HO-1. By blocking the NF-κB signaling pathway, activating Nrf2 lowers immune cell infiltration and the generation of proinflammatory cytokines (Li et al., 2014). The transcription of numerous proinflammatory cytokines (TNF-α, IL-6, IL-1β, iNOS, and COX-2) is stimulated by NF-κB, a fundamental component that influences cytokine production (Yang et al., 2020). All inducible NF-κB signaling pathways are controlled by the IκB kinase complex. Every known NF-κB activation pathway (Solt and May, 2008) uses a process in which IκBα proteins are phosphorylated on certain serine residues, thereby marking them for ubiquitination and proteasomal destruction. Phosphorylation of IκBα during inflammation triggers nuclear translocation of NF-κB, which then stimulates the production of proinflammatory cytokines (Ahmad et al., 2015). This research shows that a KD blocked nuclear translocation of NF-κB, which is accompanied by a reduction in cytoplasmic phosphorylated IκBα proteins, and dramatically reduced tissue concentrations of the proinflammatory cytokines, IL-1, IL-6, and TNF-α. Altogether, these findings suggest a potential intricate interaction between NF-κB and Nrf2, and highlight the role of Nrf2 in regulating the inflammatory response during KD therapy.

Limitations of the study include the lack of information regarding the long-term effects of a KD on learning and memory in APP/PS1 transgenic mice. The study was also limited to examination of only one mechanism of action of the KD, and did not explore other potential pathways that may affect learning and memory. To mitigate these limitations, we recommended long-term studies to evaluate sustainability of the effects and determine the optimal treatment duration. Further investigation should also be undertaken to explore alternative mechanisms of action of the KD.

In conclusion, KD aided learning and memory in APP/PS1 transgenic mice by inhibiting neuroinflammation and activating the Nrf2/HO-1 and NF-κB signaling pathways. The anti-inflammatory capabilities of a KD against Aβ-induced neurotoxicity and cognitive impairment suggest it may be a promising treatment for AD and other neurological disorders with similar pathologies.

Additional file:

Additional Figure 1 (293.5KB, tif) : The body weight of the 6-month-old mice.

Additional Figure 1

The body weight of the 6-month-old mice.

At 6 months of age, the mice receiving ketogenic diet intervention had lower body weight than those on the control diet, whereas the APP/PS1 mice on the control diet had higher body weight than the control group. n =12 per group. Data are shown as mean ± SEM. ****P < 0.0001 (one-way analysis of variance followed by Tukey’s post hoc test). ns: Not significant.

NRR-18-2767_Suppl1.tif (293.5KB, tif)

Acknowledgments:

The authors are grateful to Mathias Jucker (University of Tübingen, Germany) for kindly providing the APP/PS1 double-mutant transgenic mice.

Footnotes

Funding: This work was supported by the National Natural Science Foundation of China, Nos. 82171401, 81971187 (to SC), and 81971183 (to YT), grants from Shanghai Municipal Science and Technology Major Project, No. 2018SHZDZX05 (to SC) and Shanghai Municipal Education Commission, No. 2017-01-07-00-01-E00046 (to SC).

Conflicts of interest: The authors state that they have no conflicts of interest to disclose.

Data availability statement: The data are available from the corresponding author on reasonable request.

C-Editor: Zhao M; S-Editor: Li CH; L-Editors: Li CH, Song LP; T-Editor: Jia Y

References

  • 1.Ahmad SF, Attia SM, Bakheet SA, Zoheir KM, Ansari MA, Korashy HM, Abdel-Hamied HE, Ashour AE, Abd-Allah AR. Naringin attenuates the development of carrageenan-induced acute lung inflammation through inhibition of NF-κb, STAT3 and pro-inflammatory mediators and enhancement of IκBαand anti-inflammatory cytokines. Inflammation. 2015;38:846–857. doi: 10.1007/s10753-014-9994-y. [DOI] [PubMed] [Google Scholar]
  • 2.Anderson SR, Vetter ML. Developmental roles of microglia:A window into mechanisms of disease. Dev Dyn. 2019;248:98–117. doi: 10.1002/dvdy.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 3.Ardura-Fabregat A, Boddeke EWGM, Boza-Serrano A, Brioschi S, Castro-Gomez S, Ceyzériat K, Dansokho C, Dierkes T, Gelders G, Heneka MT, Hoeijmakers L, Hoffmann A, Iaccarino L, Jahnert S, Kuhbandner K, Landreth G, Lonnemann N, Löschmann PA, McManus RM, Paulus A, et al. Targeting neuroinflammation to treat Alzheimer's disease. CNS Drugs. 2017;31:1057–1082. doi: 10.1007/s40263-017-0483-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Asher S, Priefer R. Alzheimer's disease failed clinical trials. Life Sci. 2022;306:120861. doi: 10.1016/j.lfs.2022.120861. [DOI] [PubMed] [Google Scholar]
  • 5.Ashrafian H, Zadeh EH, Khan RH. Review on Alzheimer's disease:Inhibition of amyloid beta and tau tangle formation. Int J Biol Macromol. 2021;167:382–394. doi: 10.1016/j.ijbiomac.2020.11.192. [DOI] [PubMed] [Google Scholar]
  • 6.Atlante A, Valenti D, Latina V, Amadoro G. Dysfunction of mitochondria in Alzheimer's disease:ANT and VDAC interact with toxic proteins and aid to determine the fate of brain cells. Int J Mol Sci. 2022;23:7722. doi: 10.3390/ijms23147722. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 7.Bahn G, Jo DG. Therapeutic approaches to Alzheimer's disease through modulation of NRF2. Neuromolecular Med. 2019;21:1–11. doi: 10.1007/s12017-018-08523-5. [DOI] [PubMed] [Google Scholar]
  • 8.Bajwa E, Klegeris A. Neuroinflammation as a mechanism linking hypertension with the increased risk of Alzheimer's disease. Neural Regen Res. 2022;17:2342–2346. doi: 10.4103/1673-5374.336869. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 9.Ballard C, Gauthier S, Corbett A, Brayne C, Aarsland D, Jones E. Alzheimer's disease. Lancet. 2011;377:1019–1031. doi: 10.1016/S0140-6736(10)61349-9. [DOI] [PubMed] [Google Scholar]
  • 10.Beura SK, Dhapola R, Panigrahi AR, Yadav P, Reddy DH, Singh SK. Redefining oxidative stress in Alzheimer's disease:Targeting platelet reactive oxygen species for novel therapeutic options. Life Sci. 2022;306:120855. doi: 10.1016/j.lfs.2022.120855. [DOI] [PubMed] [Google Scholar]
  • 11.Bilkei-Gorzo A. Genetic mouse models of brain ageing and Alzheimer's disease. Pharmacol Ther. 2014;142:244–257. doi: 10.1016/j.pharmthera.2013.12.009. [DOI] [PubMed] [Google Scholar]
  • 12.Caballero MÁA, Song Z, Rubinski A, Duering M, Dichgans M, Park DC, Ewers M. Age-dependent amyloid deposition is associated with white matter alterations in cognitively normal adults during the adult life span. Alzheimers Dement. 2020;16:651–661. doi: 10.1002/alz.12062. [DOI] [PubMed] [Google Scholar]
  • 13.Ciccone L, Vandooren J, Nencetti S, Orlandini E. Natural marine and terrestrial compounds as modulators of matrix metalloproteinases-2 (MMP-2) and MMP-9 in Alzheimer's disease. Pharmaceuticals (Basel) 2021;14:86. doi: 10.3390/ph14020086. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Gibson AA, Seimon RV, Lee CM, Ayre J, Franklin J, Markovic TP, Caterson ID, Sainsbury A. Do ketogenic diets really suppress appetite?A systematic review and meta-analysis. Obes Rev. 2015;16:64–76. doi: 10.1111/obr.12230. [DOI] [PubMed] [Google Scholar]
  • 15.Guo L, Choi S, Bikkannavar P, Cordeiro MF. Microglia:key players in retinal ageing and neurodegeneration. Front Cell Neurosci. 2022;16:804782. doi: 10.3389/fncel.2022.804782. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 16.Hersant H, Grossberg G. The ketogenic diet and Alzheimer's disease. J Nutr Health Aging. 2022;26:606–614. doi: 10.1007/s12603-022-1807-7. [DOI] [PubMed] [Google Scholar]
  • 17.Hertz L, Chen Y, Waagepetersen HS. Effects of ketone bodies in Alzheimer's disease in relation to neural hypometabolism, β-amyloid toxicity, and astrocyte function. J Neurochem. 2015;134:7–20. doi: 10.1111/jnc.13107. [DOI] [PubMed] [Google Scholar]
  • 18.Hussain TA, Mathew TC, Dashti AA, Asfar S, Al-Zaid N, Dashti HM. Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes. Nutrition. 2012;28:1016–1021. doi: 10.1016/j.nut.2012.01.016. [DOI] [PubMed] [Google Scholar]
  • 19.IJff DM, Postulart D, Lambrechts DAJE, Majoie MHJM, de Kinderen RJA, Hendriksen JGM, Evers SMAA, Aldenkamp AP. Cognitive and behavioral impact of the ketogenic diet in children and adolescents with refractory epilepsy:A randomized controlled trial. Epilepsy Behav. 2016;60:153–157. doi: 10.1016/j.yebeh.2016.04.033. [DOI] [PubMed] [Google Scholar]
  • 20.Kong G, Wang J, Li R, Huang Z, Wang L. Ketogenic diet ameliorates inflammation by inhibiting the NLRP3 inflammasome in osteoarthritis. Arthritis Res Ther. 2022;24:113. doi: 10.1186/s13075-022-02802-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21.Kraeuter AK, Guest PC, Sarnyai Z. The Y-Maze for assessment of spatial working and reference memory in mice. Methods Mol Biol. 2019;1916:105–111. doi: 10.1007/978-1-4939-8994-2_10. [DOI] [PubMed] [Google Scholar]
  • 22.Krikorian R, Shidler MD, Dangelo K, Couch SC, Benoit SC, Clegg DJ. Dietary ketosis enhances memory in mild cognitive impairment. Neurobiol Aging. 2012;33:425.e19–27. doi: 10.1016/j.neurobiolaging.2010.10.006. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23.Lane CA, Hardy J, Schott JM. Alzheimer's disease. Eur J Neurol. 2018;25:59–70. doi: 10.1111/ene.13439. [DOI] [PubMed] [Google Scholar]
  • 24.Leger M, Quiedeville A, Bouet V, Haelewyn B, Boulouard M, Schumann-Bard P, Freret T. Object recognition test in mice. Nat Protoc. 2013;8:2531–2537. doi: 10.1038/nprot.2013.155. [DOI] [PubMed] [Google Scholar]
  • 25.Li L, Dong H, Song E, Xu X, Liu L, Song Y. Nrf2/ARE pathway activation, HO-1 and NQO1 induction by polychlorinated biphenyl quinone is associated with reactive oxygen species and PI3K/AKT signaling. Chem Biol Interact. 2014;209:56–67. doi: 10.1016/j.cbi.2013.12.005. [DOI] [PubMed] [Google Scholar]
  • 26.Lilamand M, Porte B, Cognat E, Hugon J, Mouton-Liger F, Paquet C. Are ketogenic diets promising for Alzheimer's disease?A translational review. Alzheimers Res Ther. 2020;12:42. doi: 10.1186/s13195-020-00615-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 27.Lilamand M, Mouton-Liger F, Di Valentin E, Sànchez Ortiz M, Paquet C. Efficacy and Safety of Ketone Supplementation or Ketogenic Diets for Alzheimer's Disease:A Mini Review. Front Nutr. 2022;8:807970. doi: 10.3389/fnut.2021.807970. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 28.Maric I, Krieger JP, van der Velden P, Börchers S, Asker M, Vujicic M, Wernstedt Asterholm I, Skibicka KP. Sex and species differences in the development of diet-induced obesity and metabolic disturbances in rodents. Front Nutr. 2022;9:828522. doi: 10.3389/fnut.2022.828522. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 29.Morgan AR, Touchard S, Leckey C, O'Hagan C, Nevado-Holgado AJ, NIMA Consortium. Barkhof F, Bertram L, Blin O, Bos I, Dobricic V, Engelborghs S, Frisoni G, Frölich L, Gabel S, Johannsen P, Kettunen P, Kłoszewska I, Legido-Quigley C, Lleó A. Inflammatory biomarkers in Alzheimer's disease plasma. Alzheimers Dement. 2019;15:776–787. doi: 10.1016/j.jalz.2019.03.007. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 30.National Research Council (2011) Guide for the Care and Use of Laboratory Animals. 8th ed. Washington, DC: The National Academies Press; [Google Scholar]
  • 31.Noh HS, Lee HP, Kim DW, Kang SS, Cho GJ, Rho JM, Choi WS. A cDNA microarray analysis of gene expression profiles in rat hippocampus following a ketogenic diet. Brain Res Mol Brain Res. 2004;129:80–87. doi: 10.1016/j.molbrainres.2004.06.020. [DOI] [PubMed] [Google Scholar]
  • 32.Nylen K, Velazquez JL, Sayed V, Gibson KM, Burnham WM, Snead OC., 3rd The effects of a ketogenic diet on ATP concentrations and the number of hippocampal mitochondria in Aldh5a1(-/-) mice. Biochim Biophys Acta. 2009;1790:208–212. doi: 10.1016/j.bbagen.2008.12.005. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 33.Overmyer KA, Thonusin C, Qi NR, Burant CF, Evans CR. Impact of anesthesia and euthanasia on metabolomics of mammalian tissues:studies in a C57BL/6J mouse model. PLoS One. 2015;10:e0117232. doi: 10.1371/journal.pone.0117232. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 34.Pan H, Wang H, Wang X, Zhu L, Mao L. The absence of Nrf2 enhances NF-κB-dependent inflammation following scratch injury in mouse primary cultured astrocytes. Mediators Inflamm. 20122012:217580. doi: 10.1155/2012/217580. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 35.Percie du Sert N, Hurst V, Ahluwalia A, Alam S, Avey MT, Baker M, Browne WJ, Clark A, Cuthill IC, Dirnagl U, Emerson M, Garner P, Holgate ST, Howells DW, Karp NA, Lazic SE, Lidster K, MacCallum CJ, Macleod M, Pearl EJ, et al. The ARRIVE guidelines 2.0:Updated guidelines for reporting animal research. PLoS Biol. 2020;18:e3000410. doi: 10.1371/journal.pbio.3000410. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 36.Rojas-Morales P, León-Contreras JC, Sánchez-Tapia M, Silva-Palacios A, Cano-Martínez A, González-Reyes S, Jiménez-Osorio AS, Hernández-Pando R, Osorio-Alonso H, Sánchez-Lozada LG, Tovar AR, Pedraza-Chaverri J, Tapia E. A ketogenic diet attenuates acute and chronic ischemic kidney injury and reduces markers of oxidative stress and inflammation. Life Sci. 2022;289:120227. doi: 10.1016/j.lfs.2021.120227. [DOI] [PubMed] [Google Scholar]
  • 37.Rojo AI, Pajares M, García-Yagüe AJ, Buendia I, Van Leuven F, Yamamoto M, López MG, Cuadrado A. Deficiency in the transcription factor NRF2 worsens inflammatory parameters in a mouse model with combined tauopathy and amyloidopathy. Redox Biol. 2018;18:173–180. doi: 10.1016/j.redox.2018.07.006. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 38.Ruskin DN, Kawamura M, Masino SA. Reduced pain and inflammation in juvenile and adult rats fed a ketogenic diet. PLoS One. 2009;4:e8349. doi: 10.1371/journal.pone.0008349. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 39.Ruth MR, Port AM, Shah M, Bourland AC, Istfan NW, Nelson KP, Gokce N, Apovian CM. Consuming a hypocaloric high fat low carbohydrate diet for 12 weeks lowers C-reactive protein, and raises serum adiponectin and high density lipoprotein-cholesterol in obese subjects. Metabolism. 2013;62:1779–1787. doi: 10.1016/j.metabol.2013.07.006. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Saha S, Buttari B, Panieri E, Profumo E, Saso L. An overview of Nrf2 signaling pathway and its role in inflammation. Molecules. 2020;25:5474. doi: 10.3390/molecules25225474. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41.Sandberg M, Patil J, D'Angelo B, Weber SG, Mallard C. NRF2-regulation in brain health and disease:implication of cerebral inflammation. Neuropharmacology. 2014;79:298–306. doi: 10.1016/j.neuropharm.2013.11.004. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 42.Schneider CA, Rasband WS, Eliceiri KW. NIH Image to ImageJ:25 years of image analysis. Nat Methods. 2012;9:671–675. doi: 10.1038/nmeth.2089. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 43.Selkoe DJ, Hardy J. The amyloid hypothesis of Alzheimer's disease at 25 years. EMBO Mol Med. 2016;8:595–608. doi: 10.15252/emmm.201606210. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 44.Sharifi-Rad M, Lankatillake C, Dias DA, Docea AO, Mahomoodally MF, Lobine D, Chazot PL, Kurt B, Tumer TB, Moreira AC, Sharopov F, Martorell M, Martins N, Cho WC, Calina D, Sharifi-Rad J. Impact of natural compounds on neurodegenerative disorders:from preclinical to pharmacotherapeutics. J Clin Med. 2020;9:1061. doi: 10.3390/jcm9041061. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 45.Shen Y, Kapfhamer D, Minnella AM, Kim JE, Won SJ, Chen Y, Huang Y, Low LH, Massa SM, Swanson RA. Bioenergetic state regulates innate inflammatory responses through the transcriptional co-repressor CtBP. Nat Commun. 2017;8:624. doi: 10.1038/s41467-017-00707-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 46.Shohayeb B, Diab M, Ahmed M, Ng DCH. Factors that influence adult neurogenesis as potential therapy. Transl Neurodegener. 2018;7:4. doi: 10.1186/s40035-018-0109-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 47.Solt LA, May MJ. The IkappaB kinase complex:master regulator of NF-kappaB signaling. Immunol Res. 2008;42(1-3):3–18. doi: 10.1007/s12026-008-8025-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 48.Szablewski L. Brain glucose transporters:role in pathogenesis and potential targets for the treatment of Alzheimer's disease. Int J Mol Sci. 2021;22:8142. doi: 10.3390/ijms22158142. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 49.Tao Y, Leng SX, Zhang H. Ketogenic diet:an effective treatment approach for neurodegenerative diseases. Curr Neuropharmacol. 2022;20:2303–2319. doi: 10.2174/1570159X20666220830102628. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 50.van Berkel AA, IJff DM, Verkuyl JM. Cognitive benefits of the ketogenic diet in patients with epilepsy:A systematic overview. Epilepsy Behav. 2018;87:69–77. doi: 10.1016/j.yebeh.2018.06.004. [DOI] [PubMed] [Google Scholar]
  • 51.Vinciguerra F, Graziano M, Hagnäs M, Frittitta L, Tumminia A. Influence of the mediterranean and ketogenic diets on cognitive status and decline:a narrative review. Nutrients. 2020;12:1019. doi: 10.3390/nu12041019. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 52.Wang C, Yang T, Liang M, Xie J, Song N. Astrocyte dysfunction in Parkinson's disease:from the perspectives of transmitted α-synuclein and genetic modulation. Transl Neurodegener. 2021;10:39. doi: 10.1186/s40035-021-00265-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 53.Webster SJ, Bachstetter AD, Nelson PT, Schmitt FA, Van Eldik LJ. Using mice to model Alzheimer's dementia:an overview of the clinical disease and the preclinical behavioral changes in 10 mouse models. Front Genet. 2014;5:88. doi: 10.3389/fgene.2014.00088. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 54.Westman EC, Yancy WS, Jr, Olsen MK, Dudley T, Guyton JR. Effect of a low-carbohydrate, ketogenic diet program compared to a low-fat diet on fasting lipoprotein subclasses. Int J Cardiol. 2006;110:212–216. doi: 10.1016/j.ijcard.2005.08.034. [DOI] [PubMed] [Google Scholar]
  • 55.Wu Y, Gong Y, Luan Y, Li Y, Liu J, Yue Z, Yuan B, Sun J, Xie C, Li L, Zhen J, Jin X, Zheng Y, Wang X, Xie L, Wang W. BHBA treatment improves cognitive function by targeting pleiotropic mechanisms in transgenic mouse model of Alzheimer's disease. FASEB J. 2020;34:1412–1429. doi: 10.1096/fj.201901984R. [DOI] [PubMed] [Google Scholar]
  • 56.Xu L, Li M, Wei A, Yang M, Li C, Liu R, Zheng Y, Chen Y, Wang Z, Wang K, Wang T. Treadmill exercise promotes E3 ubiquitin ligase to remove amyloid βand P-tau and improve cognitive ability in APP/PS1 transgenic mice. J Neuroinflammation. 2022;19:243. doi: 10.1186/s12974-022-02607-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 57.Yang L, Zhou R, Tong Y, Chen P, Shen Y, Miao S, Liu X. Neuroprotection by dihydrotestosterone in LPS-induced neuroinflammation. Neurobiol Dis. 2020;140:104814. doi: 10.1016/j.nbd.2020.104814. [DOI] [PubMed] [Google Scholar]
  • 58.Youm YH, Nguyen KY, Grant RW, Goldberg EL, Bodogai M, Kim D, D'Agostino D, Planavsky N, Lupfer C, Kanneganti TD, Kang S, Horvath TL, Fahmy TM, Crawford PA, Biragyn A, Alnemri E, Dixit VD. The ketone metabolite β-hydroxybutyrate blocks NLRP3 inflammasome-mediated inflammatory disease. Nat Med. 2015;21:263–269. doi: 10.1038/nm.3804. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 59.Zeng K, Yu X, Mahaman YAR, Wang JZ, Liu R, Li Y, Wang X. Defective mitophagy and the etiopathogenesis of Alzheimer's disease. Transl Neurodegener. 2022;11:32. doi: 10.1186/s40035-022-00305-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 60.Zhang K, Luo J. Role of MCP-1 and CCR2 in alcohol neurotoxicity. Pharmacol Res. 2019;139:360–366. doi: 10.1016/j.phrs.2018.11.030. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Additional Figure 1

The body weight of the 6-month-old mice.

At 6 months of age, the mice receiving ketogenic diet intervention had lower body weight than those on the control diet, whereas the APP/PS1 mice on the control diet had higher body weight than the control group. n =12 per group. Data are shown as mean ± SEM. ****P < 0.0001 (one-way analysis of variance followed by Tukey’s post hoc test). ns: Not significant.

NRR-18-2767_Suppl1.tif (293.5KB, tif)

Articles from Neural Regeneration Research are provided here courtesy of Wolters Kluwer -- Medknow Publications

RESOURCES